Method of eliminating fusible patterns from dental molds



S p 1931- H. c. HAGMAN 1,822,285

METHOD OF ELIMINA'I'ING FUSIBLE PATTERNS FRO! DENTAL HOLDS Filed Nov. 12, 1928 2 Sheets-Sheet 1 gwvqmbt fiarry-C-Hagman w jw dltozmqs Sept. 8, 1931.- H. c. HAGMAN 1,822,285 I METHOD OF ELIMINATING FUS IBLE' PATTERNS FROM DENTAL HOLDS Fi led Nov. 12, 1928 2 Sheets-Sheet 2 gwoemtoz Harry Gfiaqman if Patented Sept. 8, 1931 UN ED STATES PATENT, OFFICE.

-'. G. HAG-Mm, OI MINNEAPOLIS, MINNESOTA, ASSIGNOR OI ONE-HALF TO HENRY P. 3008,01 MINNEAPOLIS,,MINNESOTA narrnon or aammn'rme rrismtnrarraans raou DENTAL mom I Application filed November 1!, i988. Serial No. 818,875."

Myinvention relates to methods of eliminating fusible patterns from dental molds,

and has for its object to provide a method ,whereby the fusible patterns may be com- '5: pletely removed from the mold so as to leave a clean and true surface within the cavity of the mold in order to faithfully and. exactly reproduce from the pattern a true and flawless casting. 10' Another object of the invention resides in the method of eliminating fusible patterns from porous dental molds which consists in exposing a portion of the mold to the atmosphere, in providing a drain from the pattern through the mold and communicating with the atmosphere through the, exposedportion of the mold, in subjecting another portion of v the mold to a fluid under ressure, and'insi multaneously heating sai mold.

20" Another object of the invention consists in utilizin steam under pressure" for simultaneously lieat'ing the mold and for forcing the fusible pattern out of the mold.

In the drawings: 25 Fig. 1 is a plan view of a structure suitable for carrying out'my invention.

Fig. 2 is a longitudinal "elevational sectional view taken substantially on lines 22 V of Fig.1.

Fig. 3 is a plan sectional view taken on line of Fig. 2 with a part of the su porting structure removed to illustrate t e rere tical beneath the. same. I

, n the casting of restorations by the method heretofore commonly employed, it has been exceedingly difficult-to produce accurate castings in which all of the corners have been completely filled out and which are free from shrinkage or expansionv due: to war age or 'disfiguration of-the mold'occasioned y subjection intense for the removable of the fusible pattern, and which wouldfit the prepared teeth of the user .without a considerable '{ing was completed.

ployed considerable danger existed of injur- Q ing the mold as by warpage, shrinkage, ex

be had between the casting and the prepared ,opening 17 therethrough which is connected amount of fitting or swaging after the cast-.-

It has furthermore required a considerable plosion, disintegration and otherwise. My invention overcomes these difliculties by roviding a method whereby the restorations may be accurately cast so that a true fit may teeth or model on which t e restoration is to be fitted and which re uires a minimum amount of trimming and tting. A A device, b means of which my proved method may carried out, is shown in details in 'the drawings. i 'This device comprises a supporting structure A which includes a support B adapted to receive a dental mold C and to hold the same in proper position. The device further includes a capD movable toward or from the mold C and adapted to cap the same so-as to form a chamber communicating with a portion of "the mold. A conduit E is directly connected with a steam generator or steam pipe and is adapted to bring steam under pressure. into the chamber within the cap D. Each of these variousv parts will now be described in detail.

The supportingstructure A comprises a base .10 which has issuing upwardly therefrom at the rearward portion thereof, an upright 11. Base 10 is constructed with ears '12 and 13 which are drilled 'at 14 to receive I above the base 10. At the center of the grating B is provided aring '16 formed with an to the rim 15 by means of a number of radial arms 18. The opening 17 in ring 18 serves to lead the discharge ,from the mold C away from the same as the device operates, while said opening and the openings in the grate ingbetween arms 18 bring the lowermost portion of the mold in communication with the atmosphere. V

The mold C includes an annular tubular container 19 which is open at both ends and Spindle 26 is which is adapted to receive the composition from which the mold proper is made. This structure is adapted to rest upon the arms 18 of grating B so as to subject the lower portidn of the mold to the atmosphere and to permit of the drainage of the fusible pattern from the bottom of the mold through the said support B.

The cap D consists of a circular plate 21 constructed at the center thereof with a boss 22. The face 23 of this plate is formed stepped as indicated at 24 for a purpose to be presently described, while the boss 22 is internally threaded at 25 to permit of the attachment of said plate to a spindle 26. The end 27 of the spindle 26 is reduced in diameter to form a shoulder 28 and externally threaded to screw in the threads 25 of boss 22. By means of this construction the plate 21 is rigidly attached to the end of said spindle. preferably of cylindrical form and is mounted for vertical reciprocation within a guide 29 formed on the upper end of the upright 11 which is bored at 30 to receive said spindle.

The face 23 of plate 21 is preferably lined with a gasket 31 which is stepped to correspond with the steps 24 of said plate and fits snugly along the face of said plate. This gasket is held attached to the plate 21 at the center thereof by means of a flanged bushing 32 which is screwed into the end of the portion 27 of the spindle 26 and which firmly clamps the inner edge of the gasket 31 against the extreme end of the said spindle 26. The outer edge of gasket 31 is held attached to theplate 21 by means of a flanged ring 32 which is adapted to clamp the outer margin of said gasket the plate 21, Ring 32 is internally threaded at 35 to receive an annular burr 36 which lies against the flange 33 and forces the flange of the ring 32 toward said flange 33. This burr is constructed with a number of notches 37 extending radially across the outer face thereof in which a suitable tool, may be inserted to rotate the same and clamp the gasket 31 in place.

As previously stated, thespindle 26 is reciprocable along the guide 29 to raise and lower the cap I). The said spindle may be reciprocated as follows: Along the rearward surface of said spindle. the same is formed with rack teeth 38 which extend substantially throughout the len th thereof. Immediate ly in back of the guide 29 and formed in the upright 11 is a case 39 which incloses a pinion 40 adapted to mesh with the rack 38. This pinion is formed with a boss 41 which is threaded to receive a set screw 42 by means of which the said pinion may be securely attached to a shaft 43. The shaft 43 is journalled in a boss 44 formed on the case 39 which provides a bearing therefor. and in a second boss 45 formed on a flange 46 which against a flange 33' formed on is adapted to be screwed into a circular bore 47 forming the interior of the case providing the second bearing for said shaft. Shaft 43 extends outwardly be 0nd the boss 45 and terminates in a head 48 w ich is drilled to receive an operating handle 49. By moving the handle 49, pinion 40 may be rotated so as to raise and lower the cap D in a manner to be presently described.

For the purpose of locking the cap D from movement when in capping position, the guide 29 is slit longitudinally as indicated at 50 in'Fig. 1 and is formed with two ears 51 and 52 extending outwardly therefrom adjacent the slit 50. The car 51 is drilled at 56 while the ear 52 is correspondin ly threaded at 57. A handle 53 is formed wit a threaded spindle 54 and a shoulder 55, said spindle beingadapted to extend through the hole 56 and to screw into the threaded portion 57 of ear 52. Upon the turning of said handle 53, the shoulder thereof is caused to force the ears 51 and 52 together to rigidly clamp the spindle 26 within the guide 29 and restrain the same from movement along the bore 30.

For the purpose of supplying steam to the cap D the spindle 26 is formed with a longitudinal passageway 58 which extends completely through the same and through the bushing 32. The upper end of spindle 26 is threaded at 59 to receive the boss 60 of -a,

casting 61 in the nature of a T which is provided with a branch 62 adapted to receive a pressure gauge 63 and with a second branch 64 adapted to be connected to a steam generator. A valve 65, formed with an operating handle 66, is attached to the branch 64 and terminates in a nipple 67 to which a flexible hose 68 may beattached. This hose may be connected to any suitable source of steam such as a pipe line connected with a steam boiler or to a steam generator.

My improved method is carried out as follows: The tubular container of mold C is first placed upon a table formed with an upwardly extending conical projection. The

wax pattern which I have indicated at 69 in Fig. 3 is next supported upon a sprue pin attached to the said projection or sprue base at the apex thereof. A suitable plastic substance, such as investment or other material employing plaster of Paris as a basemay then be poured about the pattern to form a mold completely enveloping the said pattern ex-' cept for the aforementioned sprue pin on which the same is supported: The plastic material forming the mold is then permitted to set, afterwhich the mold may be removed from the table and the sprue base thereon, and the sprue pin supporting the pattern withdrawn from the same to leave a'passageway 70, bringing the pattern proper in communication with the atmosphere. The method of making such molds being well 39 and known in the casting art, I have not illustrated the structure and apparatus used in conjunction therewith in particular detail in this application. It is to be understood, however, that the molds of which the mold C is an example, can be constructed by the method above outlined, or by any other suitable method.

After the mold has been permitted to set for a length of time in the vlcinity of hour, the pattern 69 within the same, ma be eliminated by my improved method. his is accomplished as follows: The mold C is placed upon the support or grating B with the passageway 70 extending downwardly and directed above the opening 17 in said grating. The handle 53 is next operated to release the spindle 26 and handle 49rotated to bring the cap D in engagement with the top ofthe mold C. The upper edge of the tubular receptacle 19 of this mold is then brought into engagement with a portion of the gasket 3l so as to effect an air tight closure therebetween, and

to provide a space or chamber above said mold communicating with the passa eway 58 in spindle 26. When such closure as been effected, the handle 53 may be manipulated to lock the cap D from movement so as to retain the desired seal. The handle 66 ofva'lve 65 is next manipulated to turn on the steam which is maintained at a pressure preferably in'excess of two or three pounds per square inch. The apparatus is then permitted to remain with the steam turned on fora period of five minutes or'more duringwhich time steam penetrates the porous mass of the plas tic material of the mold and serves to heat and melt the fusible pattern 69 without any damage to pattern chamber. The lower portion of the mold being open to the atmosphere through pattern to be extruded from the mold through said passagewa -byithe agency of the steam pressure upon Due to 'the fact-that the mold is more or-less porous, ,the steam rapidly reaches the wax pattern'and melts'the same so as to permit of e the drainage .of the molten pattern through the passage way 70. Dueto the pressure of thesteam upon the uppermost portion of the -mold and due to the subjection of the lowermost portion of the mold to, the atmosphere,

the pattern is completely and rapidly extruded from the mold. Most of the pattern escapes through the passageway 70, while the remainder of the the body of the mold by the pressure of the steam and the heat therefrom. When the pattern has been completely eliminated from the mold by the above rocess, the mold is absolutely clean and as ree from traces of the attern as is possible. A casting can then e cast within the mold which is absolutely true and which conforms micrometrically as to size of the pattern from which it is cast.

the passageway causes the fusible t 'e; upper portion of the mold.

pattern is forced through' Restorations constructed in accordance with this process may be made to fit precisely and exactl upon the teeth or model to which they are to e applied without swaging, so that the labor of applying the restorations is greatly reduced and the service and fit of the restorashown, or may be constructed integral with the supporting structure A if desired.

My invention is highly it provides a simple met tures and similar castings where a high degree of accuracy in the reproduction of the pattern is desired. The rocess can be carried on without danger o injury to the mold and without constant attention of the attendant. With my invention, considerable time is saved to the attendant in the eliminating. of the pattern sothat the restorations ma be constructed in less time than heretofore, enabling the user to obtain accurate castings quickly. Changes in the specificsteps tion, as herein disclosed, ma be made within thescope of what is claime without departing from the spirit of my invention.

Having described my invention, what I meritorious in that 0d for forming denof my invenclaim as new and desire to protect by Letters Patent is: 1

1. The method of eliminating fusible patterns from porous molds which consists in arranging the mold with a downwardly ex- 7 pressure and simultaneously heating the mold.

3. he method of eliminating fusible patterns, from porous molds which consists in arranging the mold with a drain from the bottom of the mold, capping the top of the mold to form a chamber thereabove, introducing within said chamber a gas under pressure and simultaneously heating the mold.

4. The method of eliminating fusible patterns from porous molds which consists in arranging the mold with a drain from the bottom of the mold, capping the top of the mold to form a chamber thereabove, introducing within said chamber steam under pressure to simultaneously heat the pattern and force the same out of the mold cavity.

5. The method of eliminating fusible patproviding the mold with a portion thereof. under atmospheric pressure, in forming a chamber communicating with another por tion of said mold, in roviding a. drain com l5 municating with the usible pattern end the portion of the mold subjected to atmospheric pressure, and in a plying steam under pressure to said cham er to simultaneously heat the mold and drive the attern through said 19 drain and out of the mold In testimony whereof I have aflixed my signature to this specification. v

HARRY G. HAGMAN. 

